The Prime Minister tries to shut down debate over the date of Australia Day

Prime Minister Malcolm Turnbull is defending the date of Australia Day, saying those seeking to change it are trying to divide the nation.

Australia Day flags Source: AAP

He's posted a video message on social media after Greens leader Richad Di Natale (nuh-TAH-lee) announced his party would campaign to change the day from the 26th of January.

That's the date in 1788 the First Fleet landed in Sydney Cove, representing the beginning of British colonisation.

Many Indigenous Australians see the date as "invasion day".

Mr Turnbull says a free country debates its history, but he hasn't welcomed this debate.